Table 1: Clinical characteristic of study subjects.
| 1st trimester | 2nd trimester | 3rd trimester | Post partum | ||
| Age (yr) | 29.31 | 29.17 | 28.81 | 29.76 | |
| Height (cm) | 160.10 | 161.00 | 160.12 | 161.12 | |
| Weight (kg) | 56.62 | 57.62 | 57.62 | 57.03 | |
| Monthly salary (in RMB) | < 1000 | 13.8% | 20.7% | 11.5% | 9.1% |
| 1000-3000 | 34.5% | 55.2% | 46.2% | 36.4% | |
| 3000-5000 | 13.8% | 6.9% | 38.5% | 21.2% | |
| 5000-8000 | 13.8% | 10.3% | 0 | 15.2% | |
| 8000-10000 | 13.8% | 3.4% | 3.8% | 9.1% | |
| > 10000 | 10.3% | 3.4% | 0 | 9.1% | |
| Teeth brush per day (time) | >= 2 times | 65.5% | 72.4% | 88.5% | 81.8% |
| 1 time | 31.0% | 27.6% | 7.7% | 18.2% | |
| 0 | 3.5% | 0 | 3.8% | 0 | |
| Teeth brush time (min) | <= 1 | 17.2% | 3.4% | 11.5% | 3.0% |
| 1-2 | 58.6% | 72.4% | 53.8% | 60.6% | |
| 2-3 | 6.9% | 17.2% | 34.6% | 30.3% | |
| >= 3 | 17.2% | 6.9% | 0 | 6.1% | |
| Teeth cleaning interval | < 1 year | 6.9% | 3.4% | 0 | 18.2% |
| > 1 year | 6.9% | 10.3% | 7.7% | 9.1% | |
| Never | 86.2% | 86.2% | 92.3% | 72.7% | |